In general, when a conventional antenna system for tracking a satellite performs electronic or semi-electronic satellite tracking, the production cost of the system is increased. Further, since the antenna system performs only 2-axis control in azimuth and elevation directions, it cannot precisely track the satellite if a beam width of an antenna is narrow.
In addition, the conventional antenna system performs simple 3-axis control even when it carries out mechanical satellite tracking. Therefore, the conventional antenna system has a structural limitation that cannot appropriately cope with a satellite polarization angle error generated by a position variation of a movable body on which it is mounted, and a satellite-oriented angle error generated by a latitude variation.
Moreover, in order to reduce the size of the antenna system, a method in which all components that must be mounted thereon are disposed outside has been used. In such a case, however, there exists an inconvenience of making all the supplementary components mounted on the movable body on which the antenna system is mounted.